Year	Percent
1965	28.73376
1966	28.51248
1967	27.41318
1968	27.92737
1969	27.29524
1970	27.31634
1971	27.6997
1972	28.28805
1973	27.89251
1974	27.89791
1975	28.04863
1976	27.29467
1977	26.30516
1978	25.84356
1979	25.38151
1980	24.84472
1981	24.98561
1982	25.1243
1983	25.34191
1984	25.62627
1985	25.8515
1986	25.6105
1987	25.97877
1988	25.84863
1989	25.6348
1990	25.87916
1991	25.73998
1992	25.28505
1993	24.8661
1994	24.48727
1995	24.15072
1996	24.0561
1997	23.72674
1998	23.4399
1999	23.04636
2000	22.82115
2001	14.17215
2002	14.17029
2003	13.46913
2004	13.07354
2005	12.58997
2006	11.44907
2007	11.63761
2008	11.33366
2009	11.84861
2010	11.23415
2011	11.25874
2012	10.72275
2013	10.35622
2014	10.07448
2015	9.967
2016	9.6614
2017	9.69629
2018	9.43551
2019	9.40873
2020	9.92699
2021	9.299
2022	9.30653